Answer: Without seeing the pest, it's difficult to positively identify it, but it sounds like the willow beetle. These beetles scrape the surface or chew holes in leaves. Leaves discolor and may drop prematurely. High populations cover leaves with dark droppings and can skeletonize or defoliate entire plants. Plants can become susceptible to other problems and even die. Larvae may feed on roots but do not seriously damage established, woody plants.
Conventional pesticides such as carbaryl (Sevin), chlorpyrifos (Dursban) and acephate (Orthene) are very effective. Environmentally sound alternatives to conventional pesticides such as the bacterium, Bacillus thuringiensis var. tenebrionis (M-Trak?) are also effective.
Regardless of the material used, applications should be made to the foliage as soon as eggs hatch while larvae are still small. Older larvae are more difficult to kill and produce more damage than when they are young. Thorough coverage is essential to obtain adequate control.
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